Force YouTube to play HQ (high quality) or HD (high definition) link

Update Add: ?hd=1 to the end of the YouTube video URL and if it is available, an HD version will play.

Add:&fmt=18 to the end of the YouTube video URL will play the video in HQ (high quality).
Add:&fmt=22 to the end of the YouTube video URL will play the video in HD (high definition).

Regular: http://www.youtube.com/watch?v=SVvx13dpTEA
High Quality: http://www.youtube.com/watch?v=SVvx13dpTEA&fmt=18
High Definition: http://www.youtube.com/watch?v=SVvx13dpTEA&fmt=22

If a video is not available in HQ or HD, then they will not be able to be shown in those formats.